Cadillac is showing two rare custom-built Fleetwood convertibles manufactured in 1934 and 1937 at Pebble Beach.

Besides bringing the 2013 ATS at Pebble Beach this week, Cadillac is also showing two rare custom-built Fleetwood convertibles manufactured in 1934 and 1937. These two cars were part of the company's made-to-order Fleetwood collection, but both of them were never selected by the customers. These two vehicles are a 1934 rumbleseat roadster model 5802 and a 1937 Phaeton model 5859.

A few decades later, well-known coachbuilder and vehicle restorer Fran Roxas built the two cars from scratch, based only on the original blueprints made by John Hampshire, a Cadillac designer.

Both vehicles were recently sold at an auction, with the Roadster 5802 going for $1,001,000, while the Phaeton 5859 fetched $962,500.

Under the hood of these two vehicles is the company's massive 16-cylinder engine, while the drawings of the cars were used as an inspiration for creating the exquisite Ciel concept that will be once again be presented this week at Pebble Beach.

Rare Cadillacs showcased at Pebble Beach